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Brain Tumors

Pathological finding Tumor

Pseudorosette Ependymoma, SEGA Rosenthal fibers Pilocytic astrocytoma Rosettes Medulloblastoma Wet Keratin Craniopharyngioma Psammoma bodies Meningioma Fried egg Oligodendroglioma

Medulloblastoma - Kids, midline, Cerebellum, diffuse contrast enhancement

- Can seed in CSF (drop mets) but rarely involve meninges

- On MRS, there is a choline and taurine peak

Stains positive for Synaptophysin

Rosettes formation

Pilocytic astrocytoma: - Kids, cystic with an enhancing mural nodule.

- Can occur in optic tract in patients with NF1

- Associated with BRAF gene mutation

Pathology: Cells with long processes - Rosenthal fibers (intense red deposits formed of hyaline)

Hair like processes arranged in Rosenthal fiber Smear of pilocytic cells

bundles, resemble mats of hair

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SEGA: - In patients with TS (TSC1 in ch 9q34 and TSC2 in ch 16)

Pathology: large polygonal cells with abundant eosinophilic cytoplasm, perivascular pseudo-

rosettes

GFAP H&E

Oligodendroglioma: - Adults, lobar, associated with IDH mutation

- Anaplastic (Grade III) associated with allelic loss at ch 1p and 19q

Pathology shows rounded nuclei, prominent cytoplasm with clear halo (Fried egg)

GFAB stain H&E

Colloid cyst: - Usually arise in the 3rd ventricle close to the foramen of

Monroe

- MRI: isointense on T1, hyperintnse in T2

Pathology shows simple cuboidal or columnar epithelium,

full of proteinaceous material

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Ependymoma: - Usually arise in 4th ventricle (children) or spinal cord (adults)

- Can seed through CSF

Pathology: perivascular pseudo-rosettes (Ependymal cell processes directed towards vessel wall

with formation of perivascular anuclear zones of GFAP+ fibrillary processes)

Subependymoma: - Arise in 4th ventricle in adults, doesn’t enhance

- Clusters of cells embedded in dense glial fibrillary background, there may be pseudorosette

Hemangioblastoma: - Cystic cerebellar tumor in adults with nodule of blood vessels, can involve the spine in VHL

Pathology: vacuolated cells and vascular structures (packed thin walled vessels and large

neoplastic cells with pink to clear cytoplasm with fine vacuoles containing PAS+ lipid)

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Meningioma: Pathology shows: Psammoma bodies (laminated calcific concretions) and whorls formation (cells

arranged in whorls)

Meningothelial whorls Psammoma bodies in psammomatous meningioma

Choroid plexus papilloma: - Arise in lateral ventricle in children, homogenous enhancement

Pathology: papillary or villous architecture (single layer of epithelial cells

overlying a fibrovascular core)

Pituitary adenoma: - Rounded or polygonal cells, rounded nuclei, cytoplasm either

chromophobic, acidophilic or basophilic according to hormone production

Chromophobic GH Producing (acidophilic)

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Craniopharyngioma: - Supra-sellar tumor in children, usually

calcified

Pathology: Keratinocytes in spheres

called “wet Keratin”.

Rathke’s cleft cyst: - Supra-sellar cystic tumor, isointense, non-enhancing

Pathology: cyst lined with ciliated

columnar epithelium with goblet

cells.

Pictures from Radiopedia Picture from Medscape website

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Hypothalamic hamartoma - In children, causes gelastic seizures and precocious puberty

- MRI: non-enhancing, isointense

Pathology: hypocellular mass of mature glia and neurons

Germinoma: - Suprasellar or pineal (most common pineal tumor)

Pathology: small reactive lymphocytes and large neoplastic germ cells.

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Pineocytoma: - In Adults, low grade tumor, contrast enhancing

Pathology: characterized by large anuclear areas called pineocytomous rosettes

DNET: - Children or young adults

- MRI: Cortical, soap bubble appearance in MRI, no enhancement

Pictures from Radiopedia Non-enhancing

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CNS lymphoma: - MRI: homogenous enhancement, vasogenic edema in T2, diffusion restriction in DWI

- Usually arise at the edge of the ventricle

FLAIR T1+C

Epidermoid cyst: - Caused by entrapment of ectodermal tissue in neural tube during development

- MRI: CSF signal in T1/T2, heterogenous in FLAIR, restricted diffusion (unlike arachnoid)

Pathology: cyst lined by squamous epithelium, filled with keratin and cholesterol.

T1 + contrast T2 DWI